On Factors Related to Spontaneous Healing of Ruptured Intracranial Aneurysms

Ninety‐four intracranial aneurysms were examined with the aim of finding what spontaneous organizing processes may lead to strengthening of the aneurysmal wall. The aneurysms were examined with a dissecting microscope, by microradiography and histopathologically. The following types of changes affording protection against recurrence of subarachnoid haemorrhage were considered: a) innervation in relation to spasm close to the neck of the aneurysm, b) thrombosis of the aneurysm, c) reparative processes at the site of rupture, d) development of whole new walls, e) organizing processes related to fatty atheromatoses and calcifications, f) possible regeneration of elastic and muscular tissue, and g) formation of new blood vessels in the walls of the aneurysms. No real regeneration of elastin or medial layer seems possible; however, pre‐existing clumping fragmented elastica may be seen. During development of either a membrane or an atheroma leading to calcification, there is still a danger of rebleeding until the process is complete in relation to the aneurysmal wall, i.e., until a complete tight new sac has formed or a yellow thrombus completely filling the aneurysmal sac has developed or a complete calcification of the entire aneurysmal wall has taken place.